Working on holidays and holiday pay

There is no law requiring businesses to close on "legal" holidays--the "legal" part refers to the fact that many government functions (e.g. the post office; schools) are closed, but has no relevance to private businesses. Companies are entirely free to set their holiday policies and to decide when they are open and whether they will pay anyone a "holiday premium" or overtime for working on a holiday. If your company chooses to treat holidays as a regular work day and to not pay extra, then as long as their is no contract (including a union agreement) to the contrary, they may do this.